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HELP - Echo Cancellation

Hello, I received the task to built up an Line Echo Canceller (LEC) with the TMS320C6211. I am equipped with tha TMS320C6211 DSK. Is there anybody who has experiences with the implementation of an echo canceller on a DSP ? Is there some source code in C++ available which deals with this proble...

Re: Ultrasonic Echo canceller

goldfita@signalsguru.net wrote: > Nesert wrote: > > > Hi, > > I'm working with ultrasonic waves but I have the problem when I send a > > signal and listen for reflections of different surfaces. I need to > > diferentiate the diferent echo surfaces. How can I do this? I dont know > > what t...

Narrow band energy and echo cancellation

Hi, I am trying to implement a G.168 compliant echo canceller. I'm conversant with most aspects of cancellation, including the problems of mis-training on signal with strong continuous spectral lines. However, I have never been forced to cure this problem before. :-) It seems clear there...

Narrow band energy and echo cancellation

Steve, I can tell you a bit about the origin of CSS use in G.168. CSS was introduced to us in ITU SG-15/Q7 by Dr. Hans Gerlich of Germany. It is 44.1KHz because it was used with the artificial head and work done on perception. This should not be a big problem. You can build the signnal at 4...

Acoustic Echo Cancellation source

Hello , We are 2 students writing a VideoConference application on linux; We want to use microphones for recording and loudspeakers for hearing. Now , test we made so far show that there is acoustic echo even if there is a reasonable distance between micropone and loudspeakers. I...

Re: New Digital Audio Standard?

"Randy Yates" wrote in message news:Fl7Gb.6824$IM3.1945@newsread3.news.atl.earthlink.net... > Kirk Patton wrote: > > > Hi all . . . > > > > The point about filtering definately brings up some issues . . . > > > > While my thoughts aren't fully formed on the subject, I feel tha...

Re: echo canceller

Randy Yates wrote: > Jerry Avins writes: > > > > michael yarwood wrote: > > > > > > > data call (e.g. fax,modem etc.) setup signals that the echo cancellers > > > should be turned off. > > > wrote in message > > > news:1e5efa11.0401240729.6b2a568c@posting.google.com... > > ...

Re: C Source for VoIP Echo Cancellation

Have a look at Asterisk. John ...

Re: acoustic feedback fighter

Why does it have to be in C? Why could it not be in machine code or assembler? Or, if you wanted to illustrate that you were a tyro, in Forth?) I suggest that you read up on Echo Cancellation, a topic well-covered in the literature. (I suggest, rather than explain, because it's not yet an ar...

Cancellation

Hi all, I have read up on using echo cancellation and training FIR filter coefficients with various algorithms. All these systems rely on two uncorrelated signals to find echo paths. Does anyone know if methods exist to allow echo paths to be found using a single frequency turned on an off or...

Re: Is there an Open Source Echo Cancellation module available?

> Andrew, > > I thought about it but most of the ones I saw were in the $70+ range. Since > my software is free, I'm trying to make entry into it as cheap as possible. > I'm finding out that only a handful of my users are willing to spend more > than around $15. If you know of anything, plea...

Re: Problems after freezing FIR coefficients of Acoustic Echo Canceller

Hi Johan, What does "as soon as" really mean? The very second, or just fairly quickly after? It is a step change, or a progressive degradation? When you switch off the adaption, what phyisical action do you perform? Are you just flicking a finger to press a key, or shuffling a bunch of pe...

Preventing feedback by delay?

Hi I'm having a question about echo cancellation and feedback reduction. --------- ----- | Speaker | --------air------> | Mic | --------- ----- ^ | | ------- ----...

Echo Cancellation

Hi, I have a problem where I send a signal and listen for reflections of different surfaces but I dont want to listen for signals that are reflected of two or more surfaces. How can I use an adaptive filter to remove these kind of reflections? Any help on this topic will be greatly appreciated...

Echo Cancellation on PC platform

we want to implement an acoustic echo canceller on a windows PC platform for chatting tools like MSN/skype. A serious problem we found in this kind of platform is the time delay (sound card play+speaker+air+mic.+ sound card record) between Ref. signal and Echo signal is not consist in every sess...

Re: Onset Detection of Human Speech

"Stan Pawlukiewicz" wrote in message news:drlb5q$4hg$1@newslocal.mitre.org... > Polar wrote: > > Hello, > > > > I've pieced together a sound-localizer that is supposed to be capable > > of detecting the location (in terms of an azimuth angle) of human > > speech. > > > > ...

Re: Modem datatapping/sniffing

Vladimir Vassilevsky wrote: > > > hamid_brj wrote: > > > Can anyone help me in the way of datatapping/sniffing a dial-up modem > > connection by only access to the complex signals carries in the 2-wire > > link(listening to the voice)? > > > For the modern protocols this is ...

matlab & ccs interfacing

we are currently working on echo cancellation using adaptive filtering on dsk 6713. we have implemented fir low pass and high pass filters on the board using CCS. we have developed L.M.S algorithm in Matlab(Not the Blockset provided in Help. A new one). we want to download that m file on the boar...

Unstability in NLMS algorithm for Echo Cancellation

Hi every body, I have implemented a line echo canceller based on NLMS algorithm (TI app. note SPRA129) but sometimes the coeficient updatation falls into a bad state and echo will amplify. I changed the algorithm in a way that when I find this situation has happend I reset the coeficients to ze...

Re: Asymmetric Data Transfer Rates of Cable Modems

Steve Underwood wrote: (snip) > I have never implemented V.90, but.... > I understand the real challenges are training for the non-linear > behaviour of the u-law/A-law ADC/DACs, any translation between those > codecs occuring in the network, and any gain adjustments in the network, ...

Re: Low Standby Current DSP

Un bel giorno Steve4DSP digitò: > I should say at this point that i intend to process audio and sample at > 10kHz at least 2 ADC's and 2 DAC's concurrently... > That said, i intend to apply the adaptive echo cancellation to the 2 ADC > inputs > Maybe that would help for a mips estimatio...

Echo Cancellation - non acoustic application

all: I dont know if this will work or not, but from what I read it sounds like acoustic echo cancellation is fundamentally the same problem I have. I am recording pitch measurments with a single sensor located at the center of gravity of a vehicle. I would like to extract the road profile fro...

DSP contractor position in Sydney, AU

Hello to everybody, I apologize for getting off topic but it looks like this is the only place you can meet an experienced DSP engineer, the jobs forums are very generic and partially hopeless. I am deeply sorry. We have a position for DSP contractor (6 months to 1 year contract) in Sydn...

Re: pair-wise error probability - what's the point?

Randy Yates wrote: > glen herrmannsfeldt writes: (snip) > > But the detected symbol likely also depends on the previous symbol, > > and possibly the following symbol, so tripletwise or quadrupletwise > > could make sense. > Oh-m'gosh. That would be horribly complex. I think the un...

4th. International Signal Processing Conference

The 4th. International Signal Processing Conference offers in-depth training presented by the industry's leading companies: hundreds of peer-reviewed papers, lectures and workshops. Conference: Monday October 30-Thursday November 2, 2006 Exhibits: Tuesday October 31- 12:00 PM- 6:00 PM Wed...

Explanation of LMS algorithm using samples

Hai All, I am a beginner in the DSP domain . And now I am working on the Acoustic Echo Cancellation. I have gone through the theoretical details of LMS algorithm and I have analysed that and I understood that why we are getting each step. But when I go for sample by sample analys...

How to calculate the error signal in the LMS algorithm

Hai All, I am working with Acoustic Echo Cancellation using LMS adaptive algorithm.In that I have understood each and every step.But I am facing the problem with error calculation.If d[n] is the desired signal that is captured by the microphone and x[n] be the filtered far end si...

Acoustic Echo Cancellation using LMS algorithm with C++ coding

Hai all, I am working on Acoustic Echo Cancellation using LMS algorithm . Theoretically I went through that thorougly and now I am implementing that using C++. I am considering the 16 bit mono with 8KHz sampling frequency.As it is considered of 16 bits amplitude(intensit...

Regarding acoustic echo cancellation using frequency domain LMS algorithm and subband LMS algorithm

Dear all, I am working on the acoustic echo cancellation.I have implemented the time domain LMS algorithm for acoustic echo cancellation and it is working fine only for some audio files and not working for some other audio files which has the large eigen value spread.So to avoi...

Regarding polyphase IIR filter.

Dear All, Iam working subband acoustic echo cancellation.In that for subbanding the input signal i used polyphase IIR filter.I searched in net for polyphase IIr filter design.I got some techinical documents related to polyphase IIr filter, I mentioned important links related to do...

regarding polyphase IIR filter.

Dear All, This is the my first mail to post our group.Iam working on subband acoustic echo cancellation.In that for subbanding the input signal 2 path polyphase IIR filter is used.I searched for polyphase IIR filter design in net I got some techginical documents.In those documents one doc...

Regarding double talk detection in Acoustic Echo Cancellation

Dear Sir, I am working on Acoustic Echo Cancellation using LMS algorithm in time domain.I have written the code for this.It is working fine that its output signal has only the near end signal with a very very small hiss sound in the situation when both farend and near end signal...

Line echo cancellation - conditions for freezing adaptation

Hi com.dsp-ers, I know that there are some scenarios in which a line echo canceller should suspend the process of adapting its coefficients: 1. Double talk (the most obvious case) 2. Narrow band reference signal detected 3. Numerical overload detected I wanted to broadcast a call for ide...

TMS320C6711-Real Time Implemantation of Echo Cancellation (LMS) Algorithm

Hello Everyone As the Final Year Engineering Project we are Implementing Echo Cancellation (LMS) Algorithm in Real Time using TI's TMS320C6711 DSK. The project is in final stages and we are experiencing the following problems: 1) At the RUN time or BUILD time the following pops up "DISK I...

Regarding Acoustic Echo Cancellation with subbanding

Dear Sir, I am working on Acoustic Echo Cancellation. I have implemented both AEC without subbanding and AEC with subbanding in C+ +. For subbanding of AEC I used Polyphase IIR filter(with 70dB attenuation). AEC without subbanding is working fine. But in the outputs ...

Re: Resampling for multirate system help

> billysdomain wrote: > Why? If for some purpose, there may be a better way. If as an > assignment, all bets are off. its for a purpose, its a intercom path and the data samples get piped through a echo cancellor library which only operates at 8Khz. Is there a better way? i dont have the pr...

Re: Residual echo activity detection.

neelufar.2005 wrote: > Hi All, > > Can any one help me to get documents related to Residual echo activity > detection i.e, to detect weather the output of acoustic echo cancellation > contain residual echo or not. Thanks in advance You have been told many times already that there i...

Regarding Delay estimation in Acoustic echo cancellation

Hi, I am a fresher to the DSP field, I am going through the acoustic echo cancellation. I want help regarding delay estimation in acoustics echo cancellation. Can any one suggest me a good algorithm for this. Help me for getting good papers on this. Thanks in advance. Regards, Neelufar. ...

Need argent help regarding delay estimation

I am going through Average Magnitude Difference Function (AMDF), while exploring on this I found a good PDF Enhancing Echo Cancellation via Estimation of delay By Youhong lu,Ronald Fowler,Wenshun Tian and Leland Thompson. In which the delay estimation is done. I am going through this paper...

Re: Questions about equivalents of audio/video and digital/analog.

Arny Krueger wrote: (snip) > The reason I say that they are analog at the most fundamental level is the > fact that every line receiver I've ever seen makes some kind of > analog-domain judgement about the state of the line. Like, 0 is less than > 0.5 volts and 1 is greater than 2.7 v...